VW Passat overheating on highway

How about the water pump? How many miles on this engine as the water pump is located behind the timing belt and should be replaced when the timing belt gets replaced https://repairpal.com/estimator/volkswagen/passat choose timing belt and you can locate a shop here https://repairpal.com/volkswagen-repair-in-colorado-springs-colorado

valleyautotech may be right, check the water pump. The impellers on them can break off, and they will work OK at low speeds but not higher speeds.