Abstract: A gas separator for a submersible centrifugal pump or well has hardened cases on the components exposed to well fluid within the interior of the gas separator. The gas separator has a cylindrical sidewall with a bore. A shaft driven by a motor of the pump extends through the bore. An inducer is located in the bore for applying pressure to the fluid. In one type, a spinning guide vane imparts swirling motion for the well fluid to separate as it flows through a straight-through bore section. In another type, a tubular barrel locates in the sidewall, defining an intake chamber. The intake port in the sidewall is located above the intake port in the barrel, causing a reverse direction flow to separate gas from the liquid.