Not using antifreeze /coolant. You know the green or red stuff that goes in your radiator. It doesn't matter where you live, you need the proper fluid in your radiator. Water alone, makes things rust and clog. If you did that, you have to flush the cooling system, completely. Replace the radiator cap and thermostat. Then use anti freeze year round.

Hi No you need to replace all hoses rust in a system is what you have the one place it usually comes from is the water pump the bearing is a carbon bearing this does indicate it is wearing and will also need be replaced along with age of water instead of coolant in the system

The engine block is made of cast iron and will rust from the inside if you do not use the correct coolant to prevent his happening.

The use of plain water will cause this problem. Antifreeze contains corrosion inhibitors which stop rust and sludge forming.

When was the last time that the cooling system was drained, flushed and CLEANED?

rust in coolant , no anti-freeze has been used since