A screw-type fluid pump is provided with an elongate casing having a surface defining an internal fluid flow space and a screw within the flow path, fixed to the casing, and having a plurality of flights for continuously conveying fluid from an inlet on the casing to an outlet for appropriate disposition as the screw and casing are rotated. A conduit/torque tube extends through the screw in axially overlapping relationship with the casing over no more than one third the axial extent of the screw at the upper region of the casing. The conduit/torque tube establishes communication between a plurality of pockets between screw turns and the atmosphere to effect pressure equalization so that cavitation in the fluid flow space is prevented as the screw is operated. The conduit/torque tube also transmits the force from a rotary drive to the screw.