Water pump question Johnson 9.9

[Flounder pounder]

The impeller housing plate sits ontop of the lower unit. The rear wall of the circle that surrounds the driveshaft bearing is corroded. The<br />front wall of this circle has been built up to level with JB weld or epoxy by a mechanic in the past. My question is does this rear wall also have to be built up to level or is this how water enters the water pump via the impeller? Should the back wall be 1/4 inch lower?<br /><br />Thanks