Part of an annual service on all outdrives should be the removal of the drive, pressure test for oil leaks, water pump service and most important an inspection of the transom bearing, u-joints and all rubber bellows. These bellows are large rubber hoses that keep water from the boat and u-joint shaft. Because they are prone to punture, dry rot, and cracking they need to be checked each year and replaced every 3 yrs.
A breach of this bellows means each time you put the boat in the water the bellows fills with water and the bearings. shafts and u-joints begin to rust. Over a period of time they rust so badley that they can explode while underway a cause thousands in damage. Prevention is by far the cheaper route.
The water pump impeller is made of neoprene and is subject to wear. As always it is better to replace it annually and avoid an overheat that can leave or stranded or even damage the engine of your boat.
Regular inspection of these items and replacement before they cause other damage are key to keeping your boat running and reducing breakdown cost.
You can see from the photos that the damage from water intrusion is considerable. In each case replacement of this bellows would have prevented this damage and been much less expensive.