The screws are there to keep the wear ring from spinning, so don't worry about the holes in the jet pump housing. You'll notice how the screws will bore into the wear ring, but they won't penetrate through. Like you, the threaded portion of my jet pump housing didn't last, so I used a drill bit to slightly bore into the new wear ring, so the screws could bite. Again, be careful not to drill through the wear ring, and don't drill the holes too large.