Pump and method

A pump for pumping a liquid comprising a pump rotor configured to rotate about an axis, an axial working passage through which liquid is pumped by the pump rotor and at least one feedback passage communicating with the axial passage, the axial passage extending axially relative to the axis from an inlet to an outlet, the pump rotor being rotatably disposed in the axial working passage between the inlet and the outlet and being axially slidable within the passage, the axial working passage including a thrust surface adjacent to the pump rotor on an inlet side of the pump rotor, the thrust surface extending substantially perpendicular to the axial working passage, the thrust surface configured to limit pump rotor axial movement toward the inlet by bearing an entirety of pump rotor thrust during pump rotor operation, the feedback passage providing liquid communication between a high pressure region of the axial working passage and a region between the pump rotor and the thrust surface at the passage inlet in order to permit a portion of the pressurized liquid to be delivered from the high pressure region to the region at the passage inlet.