2002 Lexus RX 300 Oil Pump on

The oil warning light means turn the engine off immediately and coast to the side of the road, not drive it like that. The damage has been done. Replacing the oil pump is not going to solve anything. They have a very low failure rate, and even if it was bad, the engine bearings are gone and the pistons have been scuffing on the cylinder walls. The fix is a total engine rebuild or a used engine. Even if you had stopped the engine right away, the low oil pressure had already occurred and was typically caused by a "spun" bearing. That's what caused the noise. You might have avoided the need for a complete rebuild, but the crankshaft still would have to come out, and that requires removing the engine, so it would still be a big repair bill.