A gas restrictor for an intake of a horizontally oriented submersible well pump has a tubular housing and a number of apertures. A sleeve is mounted within the housing for rotation relative to the housing. The sleeve has an axially extending row of slots. At least one weight in the sleeve causes the sleeve to rotate to a position with the row of slots at the bottom of the sleeve while the well pump is oriented horizontally. The slots and apertures are arranged so that regardless of the particular orientation of the housing relative to the sleeve, at least one of the apertures will be in registry with one of the slots.