What is causing kia Sorento 2004 corrode n rust in engine?

[KiaDxb]

What could have caused rusting plus corrosion in the engine block causing it to overheat.

Thanks

[KiaDxb]

Number of reasons would have caused this it could be dirty water, lack of correct coolant and mixing coolant contaminants in the coolant. all of this will cause the corrosion in engine.