I have been cleaning radiators for decades with an old family recipe. 2 cups of Arm & Hammer washing soda mixed with hot water, and poured into the radiator after it is drained, the lower radiator hose is removed and put back on without the use of the clamp, and also removing the thermostat. Pour the solution into the radiator and fill it with water. Run the engine until it is hot, turn off the engine and pull the lower radiator hose off of the radiator and let drain till the engine is cold. Reinstall the lower radiator hose and repeat treatment until the water coming out shows no sign of rust and is white in color. Do a flush with a box of Arm & Hammer baking soda, for 10 minutes, and then let the engine cool, and do a final flush with plain water and drain. Reinstall the thermostat and lower radiator hose clamp, and fill with antifreeze and distilled water. Never have lost a water pump using this method. It does clean out the scum inside of the block that water itself can't touch. If you look at the antifreeze it will be a green color just like it was when you installed it because it puts a protective layer onto the inside of the block that is supposed to protect the engine from rust, but in reality, with age, the rust inhibitors wear out and most people don't change antifreeze according to the maintenance schedule.
Most water pump failures don't lead to them seizing and I believe that the other person will find that a belt tensioner or alternator is the actual problem. No mater what it is, they will only find out once they remove the belt and attempt to turn every item that is supposed to turn but doesn't. This isn't rocket science, but common sense. I have always felt that if someone can't figure out something as simple as a belt not turning, then they most likely will get into bigger trouble if they attempt a repair of the cause. Some people are mechanical by nature and others are not, and there is nothing to be ashamed of to admit that it is beyond your capabilities. That is what makes us all different. I know of doctors that can do intricate surgeries, but don't or don't want to learn how to hold a wrench or screwdriver. It is not in their DNA to be anything other than a mechanic that works on human bodies, not cars or tractors. My veterinarian is just the opposite, he can do intricate surgeries with ease, and he uses a tractor, and knows how to repair it when necessary. He is also an accomplished woodworker and cabinet maker.