A cryogenic submerged multi-stage pump assembly, comprising: a vertically oriented pump shaft; an electrical motor (34,36) comprising a rotor attached to the pump shaft and a stator disposed about the rotor, wherein the electrical motor comprises a permanent magnet electrical motor; a first-stage impeller assembly (STAGE 1) comprising a first impeller attached to the pump shaft, the first impeller configured to move a cryogenic fluid from a first impeller inlet to a first impeller outlet (18,19) when the pump shaft is rotated by the electric motor (34,36), and a first impeller housing disposed about the first impeller and configured to channel the cryogenic fluid once it exits the first impeller outlet (18,19); and a second-stage impeller assembly (STAGE 2) comprising a second impeller attached to the pump shaft, the second impeller configured to move the cryogenic fluid from the first impeller housing (18,19) to a second impeller inlet and then to a second impeller outlet (18,19) when the pump shaft is rotated by the electric motor (34,36), and a second impeller housing (18,19) disposed about the second impeller and configured to channel the cryogenic fluid once it exits the second impeller outlet (18,19) to a discharge tube or discharge outlet (22, 24, 25, 26, 43, 49); wherein the first-stage impeller assembly (STAGE 1) is disposed below the second-stage impeller assembly (STAGE 2), and where the second-stage impeller assembly (STAGE 2) is disposed below the permanent magnet electrical motor (34,36); wherein the rotor comprises four magnetic poles, characterized in that the pump shaft comprises a magnetic stainless steel shaft, and in that the magnetic poles are secured to the magnetic stainless steel shaft by magnetic force and by a circumferential non-magnetic sleeve that prevents centrifugal forces of rotation from detaching the poles during motor operation. a vertically oriented pump shaft; an electrical motor (34,36) comprising a rotor attached to the pump shaft and a stator disposed about the rotor, wherein the electrical motor comprises a permanent magnet electrical motor; a first-stage impeller assembly (STAGE 1) comprising a first impeller attached to the pump shaft, the first impeller configured to move a cryogenic fluid from a first impeller inlet to a first impeller outlet (18,19) when the pump shaft is rotated by the electric motor (34,36), and a first impeller housing disposed about the first impeller and configured to channel the cryogenic fluid once it exits the first impeller outlet (18,19); and a second-stage impeller assembly (STAGE 2) comprising a second impeller attached to the pump shaft, the second impeller configured to move the cryogenic fluid from the first impeller housing (18,19) to a second impeller inlet and then to a second impeller outlet (18,19) when the pump shaft is rotated by the electric motor (34,36), and a second impeller housing (18,19) disposed about the second impeller and configured to channel the cryogenic fluid once it exits the second impeller outlet (18,19) to a discharge tube or discharge outlet (22, 24, 25, 26, 43, 49); wherein the first-stage impeller assembly (STAGE 1) is disposed below the second-stage impeller assembly (STAGE 2), and where the second-stage impeller assembly (STAGE 2) is disposed below the permanent magnet electrical motor (34,36); wherein the rotor comprises four magnetic poles, characterized in that the pump shaft comprises a magnetic stainless steel shaft, and in that the magnetic poles are secured to the magnetic stainless steel shaft by magnetic force and by a circumferential non-magnetic sleeve that prevents centrifugal forces of rotation from detaching the poles during motor operation.