Rotary pump with immersed rotor

A rotary pump for taking in a liquid, the pump comprising a pump wheel secured to a rotor immersed in a portion of said liquid taken in by the pump, a motor comprising a stator element mounted in a case, and a rotor element mounted on the rotor to rotate the rotor about an axis, means for supporting and guiding the rotor, and protective means for protecting the stator element of the motor from said liquid, the rotor having at least one groove formed in an outer surface covered by said portion of the liquid, the pump being characterized in that the means for supporting and guiding the rotor comprise first and second radial active magnetic bearings disposed at opposite ends of the motor, in that liquid recirculation grooves are formed in the outer surface of the rotor in zones situated between the motor and each of the first and second radial magnetic bearings, and in that each liquid recirculation groove is formed around an outline of the rotor situated in a plane that is substantially perpendicular to the axis of rotation, whereby inertial effects due to said portion of the liquid during radial displacements of the rotor are reduced.