Preheat the oven to 375°. In a medium saucepan, combine the water, butter, wine, salt and pepper and bring to a boil over moderate heat. Add the flour all at once and beat with a wooden spoon until the dough is smooth and gathers into a ball, about 1 minute. Remove from the heat and let stand until cooled slightly, about 5 minutes. Beat in 1 egg at a time, beating until the dough is smooth and slightly sticky between additions. Stir in the Gruyère.