Abstract: The present invention is directed to the prevention of gas lock in submergible reciprocating insert pumps typically employed in oil and gas wells. A plurality of openings are formed in the midportion of the body of the pump barrel. These openings allow fluid from the tubing string to enter the intake chamber of the barrel during a portion of the upstroke permitting equilibration of the pressure differential therebetween. Commercially available pumps can be modified easily to provide a pump in accordance with this invention.