A heart assist device, comprising: a rotor (14a, 14b, 14c, 14d, 14e); a pump housing (12a, 12b, 12c, 12d, 12e); said rotor (14a, 14b, 14c, 14d, 14e) comprising a shaft with an outer surface and an impeller extending from the shaft at a first location on the outer surface; said outer surface comprising an outer bearing surface at a second location on the shaft, and an axial bearing at or adjacent to the outer bearing surface; the axial bearing configured to be disposed axially adjacent the leakage inlet of the housing; and said pump housing (12a, 12b, 12c, 12d, 12e) comprising one or more cylindrical bores (26, 28) configured to define a pumping chamber and an inner bearing surface within the pump housing; wherein, in an operating configuration, the rotor (14a, 14b, 14c, 14d, 14e) is positioned within the one or more cylindrical bores (26, 28) such that the impeller rotates within the pumping chamber upon actuation of the rotor (14a, 14b, 14c, 14d, 14e); wherein said inner bearing surface of the pump housing is closely fitted to said outer bearing surface of said shaft to form an annular clearance there between such that during actuation of the rotor (14a, 14b, 14c, 14d, 14e) the inner bearing surface and outer bearing surface form a hydrodynamic journal bearing; wherein the pump housing comprises a leakage inlet in fluid communication with the annular clearance; wherein during actuation of the rotor (14a, 14b, 14c, 14d, 14e) the annular clearance operates as a leakage path to allow the flow of blood into the leakage inlet, and along the length of the annular clearance between the inner bearing surface and outer bearing surface; and wherein the axial bearing comprises a plurality of grooves forming a hydrodynamic thrust bearing with a mating surface of the one or more cylindrical bores (26, 28) for opposing axial thrusting of the rotor and promoting blood flow into the leakage flow path from the leakage inlet. a rotor (14a, 14b, 14c, 14d, 14e); a pump housing (12a, 12b, 12c, 12d, 12e); said rotor (14a, 14b, 14c, 14d, 14e) comprising a shaft with an outer surface and an impeller extending from the shaft at a first location on the outer surface; said outer surface comprising an outer bearing surface at a second location on the shaft, and an axial bearing at or adjacent to the outer bearing surface; the axial bearing configured to be disposed axially adjacent the leakage inlet of the housing; and said pump housing (12a, 12b, 12c, 12d, 12e) comprising one or more cylindrical bores (26, 28) configured to define a pumping chamber and an inner bearing surface within the pump housing; wherein, in an operating configuration, the rotor (14a, 14b, 14c, 14d, 14e) is positioned within the one or more cylindrical bores (26, 28) such that the impeller rotates within the pumping chamber upon actuation of the rotor (14a, 14b, 14c, 14d, 14e); wherein said inner bearing surface of the pump housing is closely fitted to said outer bearing surface of said shaft to form an annular clearance there between such that during actuation of the rotor (14a, 14b, 14c, 14d, 14e) the inner bearing surface and outer bearing surface form a hydrodynamic journal bearing; wherein the pump housing comprises a leakage inlet in fluid communication with the annular clearance; wherein during actuation of the rotor (14a, 14b, 14c, 14d, 14e) the annular clearance operates as a leakage path to allow the flow of blood into the leakage inlet, and along the length of the annular clearance between the inner bearing surface and outer bearing surface; and wherein the axial bearing comprises a plurality of grooves forming a hydrodynamic thrust bearing with a mating surface of the one or more cylindrical bores (26, 28) for opposing axial thrusting of the rotor and promoting blood flow into the leakage flow path from the leakage inlet.