These are called water rose apples or water apples. However, they look more like pears than apples. The fruit have a watery texture although not as much as watermelon. They taste slightly sweet but I have bought fruit that tasted bitter and not pleasant.
The fruit bruised easily and do not keep well. The fruit is often eaten with a sprinkling of ground salted preserved plum to enhance the flavour and texture.
I saw this tree bearing lots of fruit near my house. I didn't not take snapshots of the whole tree as the owner covered most of the fruit with plastic and newspaper as protection from bugs.