I recommend using a few different fabrics when making diaper inserts. You can use basically any fabric that has a 'soaking' capability, but some fabrics work better then others.
When you use my recommended fabrics for diaper inserts, you get a diaper insert AND a diaper soaker. A diaper insert is what you put inside a pocket diaper....this doesn't touch the babies skin. A diaper soaker is a 'lay in' type of soaker that typically goes against the baby's skin.
My recommended fabrics in this diaper insert pattern are Bamboo fleece, ZORB and Microterry. One side is a soft, moisture wicking bamboo fabric that gathers moisture yet still feels dry. This is an excellent fabric to keep against your baby's skin as a lay in soaker. The other side is a fast absorbing microfiber with a sandwiched ZORB layer. The opposite side of the insert has a very thirsty microfiber fabric. When you use this as an insert, it sucks up moisture faster then anything!
Finally, I use a ZORB layer in the center of the diaper insert. This not only makes the insert incredibly absorbent, but it also keeps the microfiber from having 'compression leaks'.
Compression leaks are what typically happens to inserts or soakers that are 100% microfiber. The microfiber is thirtsty and sucks up moisture fast, but it can't hold it when the baby "squishes" it by sitting on it. ZORB and bamboo hold fluid exceptionally well, which is why I chose to pair the two with the fast absorbing microfiber.
Check out this diaper insert pattern - it's free! It's my favorite and what I choose to use for my babies and what I recommend for my customers.
Not only that, but you can see how stinkin easy my patterns are by viewing it. :)