The pump impeller for single-stage pump/motor units, in which the motor rotor forms with the pump impeller a rotating unit which is supported on only one stationary ball and which is separated from the stator of the motor by a spherical magnetically permeable partition, consists of two three-dimensionally shaped plastic parts and a thick-walled sheet-metal plate which is designed as a cover plate for the blade channels and at the same time serves as a counterweight for compensating the rotor weight.
