I've never heard of such a thing, and frankly I wouldn't trust using one.
Everything in Peru is through contacts, and this includes renting beach houses. At my beach, for example, the renters need to get signatures from at least three owners at the beach to be allowed to rent. Unless the renter happens to know people at the beach already, this is generally handled by the owner using his or her contacts to arrange things. Having some outside company handle that just wouldn't fly.
And would you be comfortable with someone staying at your beach house that you never met yourself and vetted? I sure wouldn't. A rental company would just see dollar signs and not be looking out for your property the way you would.
Just FYI, beach houses are awesome but they are NOT investments. The money earned from rent for the whole season covers the maintenance and the mortgage interest (or the "economic cost" of having money tied up in the beach house if you have no mortgage). That's about it. I'm guessing you already know this and are fine with it, but just wanted to point it out to be sure.
If such a company exists and can do the job effectively, I think your best bet is to check with the administrative office at the particular beach. They'd be the ones who would best know if there is a company that has rented effectively before.