Like some, we have converted one of the heads on our boat to electric for the sake of simplicity and ease of use, primarily for my (much) better half and daughter but also for guests that are often unfamiliar with the operation of a marine head. Our conversion was made with the Jabsco kit below:
This device actually works quite well and has good endurance. Unfortunately though, we finally lost the impeller in the raw water intake chamber, which threw a vane (after 9 years, a pretty long service life, however). A rebuild is/was not difficult, nor particularly time consuming, but is inconvenient and especially so if one were on a cruise. And getting to the impeller is sufficiently difficult that one cannot readily swap it out as a routine maintenance operation as we do with the impellers on our engine, generator et al.
Considering the foregoing, it occurred to me that a relatively quick and easy treatment that can preserve and extend the life of an impeller in such an arrangement somewhat is the introduction of head lube into the raw water stream via the raw water strainer. (I thought others might find the approach useful.) Essentially, I removed the raw water strainer bowl, cleaned it, and partially filled it with West Marine Head Lube and a few drops of food coloring. With this, the head lube can be pulled into the impeller chamber with a few pulses of the pump (as confirmed by the appearance of the food coloring in the water around the rim of the bowl). Interestingly, the pump also runs some more quietly, at least for awhile. I intend to use the same approach with the manual toilet in our our forward head to get the lubricant into the top of the pump assembly; and, with the raw-water wash-down pump to lubricate the impeller in that device.