If there are several pieces on the frame of your pool that are beginning to rust and break off creating jagged edges around the inside of the pool can those pieces be replaced?

Normally they can be replaced. go to the manufacturer of the pool and ask for the replacement parts. if this cant be done take a careful measurement of the pieces that need replacement and you should be able to have them made to order by a sheet metal work shop in whatever material you prefer. however you will probably have to drain the pool to do the repairs.