Your solution is a NEW pump. When a pump seal leak is allowed to continue, it only makes things worse. Chas is right, without attention, you can see the chemical affect on the parts and when corrosion is obvious, you are wasting your time and money to attempt any repairs that will be long lasting.
As the pump seal leaks, centrifugal force causes the chemically treated water to travel back into the motor washing the lubricants out of the bearings. With a new seal installed, you deny water to the bearings that now run dry making noise and eventually seizing up usually within six months.
Imagine paying me to replace the pump seal and have that occur. This now enters the area where the customer says, "every since you fixed it I have had this problem."
Secondly, when you damage the impeller, replace it. When you try to repair it, keep in mind it makes 3400 revolutions per minute, or 56 per second. Proper balance of the impeller is a critical concern with centrifugal force.
Best advice, cut your losses now, and replace the pump.