In a small skillet, heat oil over medium-low heat. Thinly slice red onion, bell pepper, and zucchini. Add to skillet and sauté, stirring, until soft, about 5 minutes. In a separate skillet, heat wraps. Spread half of the hummus down the middle of each wrap. Divide spinach between wraps, then top with sautéed vegetables. Sprinkle with feta, oregano, and olives. Fold edges over to roll up, and cut in half cross-wise.