A vapor compression system (20; 220; 320) comprising: a compressor comprising: a housing assembly having a suction port and a discharge port and a motor compartment; an electric motor having a stator within the motor compartment and a rotor within the stator, the rotor being mounted for rotation about a rotor axis; one or more working elements coupled to the rotor to be driven by the rotor in at least a first condition so as to draw refrigerant fluid in through the suction port and discharge said refrigerant fluid out from the discharge port; one or more bearing systems (66, 68) supporting the rotor and/or the one or more working elements, and one or more bearing feed passages coupled to the bearings to pass refrigerant fluid along a supply flowpath to the bearings; a mechanical pump (130; 330) positioned to drive refrigerant fluid along the supply flowpath to the one or more bearings; a first heat exchanger downstream of the discharge port along a refrigerant primary flowpath in a first operational mode; an expansion device downstream of the first heat exchanger along the primary flowpath in the first operational mode; and a second heat exchanger downstream of the expansion device and coupled to the suction port to return refrigerant fluid in the first operational mode, the system further comprising: an ejector (140, 150) having: a motive flow inlet (142, 152), coupled to the mechanical pump to receive refrigerant fluid from the mechanical pump; a suction flow inlet (144, 154); and an outlet (146, 156). a compressor comprising: a housing assembly having a suction port and a discharge port and a motor compartment; an electric motor having a stator within the motor compartment and a rotor within the stator, the rotor being mounted for rotation about a rotor axis; one or more working elements coupled to the rotor to be driven by the rotor in at least a first condition so as to draw refrigerant fluid in through the suction port and discharge said refrigerant fluid out from the discharge port; one or more bearing systems (66, 68) supporting the rotor and/or the one or more working elements, and one or more bearing feed passages coupled to the bearings to pass refrigerant fluid along a supply flowpath to the bearings; a housing assembly having a suction port and a discharge port and a motor compartment; an electric motor having a stator within the motor compartment and a rotor within the stator, the rotor being mounted for rotation about a rotor axis; one or more working elements coupled to the rotor to be driven by the rotor in at least a first condition so as to draw refrigerant fluid in through the suction port and discharge said refrigerant fluid out from the discharge port; one or more bearing systems (66, 68) supporting the rotor and/or the one or more working elements, and one or more bearing feed passages coupled to the bearings to pass refrigerant fluid along a supply flowpath to the bearings; a mechanical pump (130; 330) positioned to drive refrigerant fluid along the supply flowpath to the one or more bearings; a first heat exchanger downstream of the discharge port along a refrigerant primary flowpath in a first operational mode; an expansion device downstream of the first heat exchanger along the primary flowpath in the first operational mode; and a second heat exchanger downstream of the expansion device and coupled to the suction port to return refrigerant fluid in the first operational mode, a motive flow inlet (142, 152), coupled to the mechanical pump to receive refrigerant fluid from the mechanical pump; a suction flow inlet (144, 154); and an outlet (146, 156).