A drive system for a fluid displacement pump includes an electric motor, a drive coupled to the rotor at a first end of the electric motor, a fluid displacement member mechanically coupled to the drive, and a pump frame mechanically coupled to the electric motor. The electric motor includes a stator and a rotor disposed on an axis. The drive coupled to the rotor converts the rotational output to a linear, reciprocating input to the fluid displacement member. The rotor is disposed about the stator to rotate about the stator.