Bring a large pot of lightly salted water to boiling.
In a large skillet, simmer diced tomatoes with marinara plus the liquid from the artichoke hearts over medium-high heat. Once simmering, cook for 10 minutes or until some of the liquid has evaporated.
Meanwhile, cook orzo in the boiling water as directed. Drain well and transfer to a large serving bowl.
Stir artichoke hearts and shrimp into sauce. Simmer 5 minutes, stirring occasionally, until cooked through. Add to orzo in bowl; toss with cheese.