All of the Disney resorts are open to the public, including
DVC resorts. Anyone may visit the resort, shop, dine, use recreational facilities like boat and bike rentals. So having your guests visit for the day would be no problem at all.
The pool, however, would be a problem. The rule for all Disney resorts, including DVC, is that only guests of the resort (not their guests) may use the pool. SAB will check resort IDs of everyone in the party before allowing entrance to the pool area, and other resorts do random resort ID checks and ask non-guests to leave the pool area.
If the pool is not busy, the lifeguards sometimes allow guests of guests at the pool. You can certainly ask the lifeguards if your friends may join you at the pool that day. But do ask, don't just assume it'll be OK if the pool isn't busy. The resorts seem to be stepping up enforcement at the pools, even when they're not busy, and it would be embarrassing for your guests to be asked to leave.
