Heat water in a covered saucepan. When boiling, add orzo and cook until almost al dente, about 5 minutes.
Meanwhile, heat oil in pan over medium high heat. Add garlic, leeks, and zucchini and sauté for about 5 minutes. Add the mushrooms and artichoke hearts and sauté for 5 more minutes.
Drain orzo and put in baking dish. Mix in marinara sauce, salt and pepper.
Place zucchini mixture over top of orzo and sprinkle with cheese.