A pump system includes a pump barrel disposed within a housing. A standing valve is disposed at a first end of a pump chamber defined within the pump barrel. A traveling valve is disposed at a second end of the pump chamber. The traveling valve is movable relative to along an axial axis and relative to the housing. A motor stator is disposed inside the housing. produces a rotating electromagnetic field upon receiving electrical power. A motor rotor is rotatably supported within the motor stator and rotates about the axial axis in response to the rotating electromagnetic field. A traveling plug is coupled to the valve body of the traveling body and arranged to move linearly along the axial axis in response to rotation of the motor rotor. The pump system can be disposed in a wellbore to lift fluids up a tubing in the wellbore.