What is the main conflict in Monkey by Ch'Eng-En Wu?

Monkey by Wu Ch'eng-en and translated by Arthur Waley is a story about the Stone Monkey King and his journey, along with Hsuan Tsang and others, to get scrolls from Buddha's paradise in India and take them back to China. Along the way the group must fight demons, Immortals, save the innocent, and walk the path of Buddha without fail.