A well pump assembly, comprising: a plurality of modules including a pump and a motor; the pump having first and second components that rotate against each other, the first component comprising an impeller, and the second component comprising a diffuser; the body of the first component comprising a sleeve bonded to a cylindrical wall of the impeller; and the body of the second component comprising a solid ring bonded to a cylindrical wall of the diffuser against which the faces of the inserts slide; characterized by: a plurality of inserts embedded in a body of the first component, each of the inserts having a face that is flush with a wear surface of the body of the first component; wherein the body of the first component is formed of a nickel iron alloy material; the inserts are formed of tungsten carbide; and the body of the second component is formed of tungsten carbide; wherein the body of the first component comprises: a cylindrical wall coaxial with a longitudinal axis and having inner and outer diameter surfaces, the wear surface being defined by one of the inner and outer diameter surfaces; and wherein each of the inserts is embedded in the cylindrical wall, each of the inserts having an insert axis located on a radial line of the longitudinal axis; the inserts are located in upper, lower and intermediate adjacent circumferential rows that circumscribe the cylindrical wall perpendicular to the longitudinal axis; and the insert axes in the intermediate circumferential row are rotationally offset with the insert axes of the inserts in the upper and lower rows relative to the longitudinal axis such that sinuous flow paths develop along the eroded cylindrical exterior of the body. a plurality of modules including a pump and a motor; the pump having first and second components that rotate against each other, the first component comprising an impeller, and the second component comprising a diffuser; the body of the first component comprising a sleeve bonded to a cylindrical wall of the impeller; and the body of the second component comprising a solid ring bonded to a cylindrical wall of the diffuser against which the faces of the inserts slide; characterized by: a plurality of inserts embedded in a body of the first component, each of the inserts having a face that is flush with a wear surface of the body of the first component; wherein the body of the first component is formed of a nickel iron alloy material; the inserts are formed of tungsten carbide; and the body of the second component is formed of tungsten carbide; wherein the body of the first component comprises: a cylindrical wall coaxial with a longitudinal axis and having inner and outer diameter surfaces, the wear surface being defined by one of the inner and outer diameter surfaces; and wherein each of the inserts is embedded in the cylindrical wall, each of the inserts having an insert axis located on a radial line of the longitudinal axis; the inserts are located in upper, lower and intermediate adjacent circumferential rows that circumscribe the cylindrical wall perpendicular to the longitudinal axis; and the insert axes in the intermediate circumferential row are rotationally offset with the insert axes of the inserts in the upper and lower rows relative to the longitudinal axis such that sinuous flow paths develop along the eroded cylindrical exterior of the body. a plurality of inserts embedded in a body of the first component, each of the inserts having a face that is flush with a wear surface of the body of the first component; wherein the body of the first component is formed of a nickel iron alloy material; the inserts are formed of tungsten carbide; and the body of the second component is formed of tungsten carbide; wherein the body of the first component comprises: a cylindrical wall coaxial with a longitudinal axis and having inner and outer diameter surfaces, the wear surface being defined by one of the inner and outer diameter surfaces; and wherein each of the inserts is embedded in the cylindrical wall, each of the inserts having an insert axis located on a radial line of the longitudinal axis; the inserts are located in upper, lower and intermediate adjacent circumferential rows that circumscribe the cylindrical wall perpendicular to the longitudinal axis; and the insert axes in the intermediate circumferential row are rotationally offset with the insert axes of the inserts in the upper and lower rows relative to the longitudinal axis such that sinuous flow paths develop along the eroded cylindrical exterior of the body. a cylindrical wall coaxial with a longitudinal axis and having inner and outer diameter surfaces, the wear surface being defined by one of the inner and outer diameter surfaces; and wherein each of the inserts is embedded in the cylindrical wall, each of the inserts having an insert axis located on a radial line of the longitudinal axis; the inserts are located in upper, lower and intermediate adjacent circumferential rows that circumscribe the cylindrical wall perpendicular to the longitudinal axis; and the insert axes in the intermediate circumferential row are rotationally offset with the insert axes of the inserts in the upper and lower rows relative to the longitudinal axis such that sinuous flow paths develop along the eroded cylindrical exterior of the body.