No, Albert Einstein was not aware of the existence of quarks or the specific structure of protons and neutrons. The concept of quarks and their role in forming nucleons (protons and neutrons) emerged after Einstein's lifetime.
Quarks were proposed as fundamental particles carrying fractional electric charges by Murray Gell-Mann and George Zweig in the 1960s, long after Einstein's death in 1955. The quark model and the understanding of protons and neutrons as composed of three quarks came about as a result of experimental discoveries and theoretical advancements in particle physics.
Einstein's contributions to physics were primarily in the fields of relativity, quantum mechanics, and the understanding of gravity. His groundbreaking theories, such as the theory of relativity (special and general), the photoelectric effect, and the concept of mass-energy equivalence (E=mc²), revolutionized our understanding of the physical world. However, the specifics of subatomic particles and the quark model were developed by subsequent generations of physicists.