Abstract: A submersible electric motor driven pump includes a motor assembly having an elongated tubular motor housing, an electric motor disposed in the motor housing, and a rotary motor shaft having an output end which extends from the electric motor; and a pump assembly including an elongated tubular pump housing, a driven pump shaft having external spline teeth at an end thereof, and at least one centrifugal impeller disposed on the pump shaft. A drive coupling is fixed to the output end of the motor shaft and has internal spline teeth which are slidably engaged with the external spline teeth of the pump shaft. The drive coupling transmits rotational power from the electric motor to the pump shaft, with the end of the pump shaft being operative to float axially within the drive coupling. A flanged interface surrounds the drive coupling and rigidly joins the motor assembly and the pump assembly together coaxially end to end in a sealed manner.