An impeller (30, 40) for a centrifugal pump, the impeller comprising: a disc-shaped shroud having a central axis, and a central hub circumscribing the central axis, wherein the central hub of the shroud has a first outer diameter and defines an opening; a disc-shaped base plate having a central axis coaxial with the central axis of the shroud, the base plate having a plurality of vanes extending from a first surface of the base plate, wherein the base plate includes a central hub extending axially from the first surface of the base plate, the central hub of the base plate having a second outer diameter which is less than the first outer diameter and defining a second opening; wherein the shroud includes a plurality of serrations formed circumferentially along a periphery of the shroud, wherein the plurality of serrations of the shroud includes a plurality of major teeth and a plurality of minor teeth such that multiple minor teeth of the plurality of minor teeth are interposed between adjacent ones of the plurality of major teeth; wherein the base plate includes a plurality of serrations formed circumferentially along a periphery of the base plate, wherein the plurality of serrations of the base plate includes a plurality of major teeth and a plurality of minor teeth arranged such that multiple minor teeth are arranged between adjacent ones of the plurality of major teeth, wherein each of the plurality of vanes are aligned with each of the plurality of major teeth such that circumferential sides on an end of each vane are disposed between circumferential sides of the major teeth of the base plate and the major teeth of the shroud, wherein the shroud is mounted against the base plate, and wherein each one of the plurality of serrations of the shroud has a first width measured axially and wherein each one of the plurality of serrations of the base plate has a second width measured axially, wherein the first width is less than the second width. a disc-shaped shroud having a central axis, and a central hub circumscribing the central axis, wherein the central hub of the shroud has a first outer diameter and defines an opening; a disc-shaped base plate having a central axis coaxial with the central axis of the shroud, the base plate having a plurality of vanes extending from a first surface of the base plate, wherein the base plate includes a central hub extending axially from the first surface of the base plate, the central hub of the base plate having a second outer diameter which is less than the first outer diameter and defining a second opening; wherein the shroud includes a plurality of serrations formed circumferentially along a periphery of the shroud, wherein the plurality of serrations of the shroud includes a plurality of major teeth and a plurality of minor teeth such that multiple minor teeth of the plurality of minor teeth are interposed between adjacent ones of the plurality of major teeth; wherein the base plate includes a plurality of serrations formed circumferentially along a periphery of the base plate, wherein the plurality of serrations of the base plate includes a plurality of major teeth and a plurality of minor teeth arranged such that multiple minor teeth are arranged between adjacent ones of the plurality of major teeth, wherein each of the plurality of vanes are aligned with each of the plurality of major teeth such that circumferential sides on an end of each vane are disposed between circumferential sides of the major teeth of the base plate and the major teeth of the shroud, wherein the shroud is mounted against the base plate, and wherein each one of the plurality of serrations of the shroud has a first width measured axially and wherein each one of the plurality of serrations of the base plate has a second width measured axially, wherein the first width is less than the second width.