The wash pump consists of an electric motor, pump bakplate and seal ,impeller and pump outlet Front plate...this usually comes as a one piece assembly, you may get the frontplate etc as separate pieces but latest model they plastic weld both halves of the pump housing together.With regard to removing the pump usually is 2 screws in the rear then the pump pulls down and out of the sump seal, the sump seal can be replaced separately.
Kenjo
June 2014