Bring a large pot of salted water to a boil.
Add the rotini pasta and cook according to package instructions until al dente.
Drain the pasta and rinse under cold water to stop the cooking.
In a large mixing bowl, combine the cooled pasta and basil pesto.
Gently fold in the halved cherry tomatoes and mozzarella balls.
Add the toasted pine nuts and arugula, mixing well.
Season with salt and pepper to taste.
For added flavor, sprinkle grated Parmesan cheese on top if desired.
Cover the bowl and refrigerate for at least 30 minutes.
Serve chilled or at room temperature.