If your kids aren't finding it easy making friends in public school, leaving them there may not change that. Plus, if you're considering homeschooling your kids, there are likely reasons that you have for doing it that are separate from socialization.
Children having friends within their narrow age cohort isn't the most important factor in their lives. It is actually just as valuable for them, or perhaps more so, to spend time around and get to know people of all ages, both older and younger. Learning how to relate to small kids will help them be parents, teach them patience, and allow them to share their knowledge. Learning to speak with and relate to adults and older children will give them more confidence as they get older and give them even more sources for learning. Plus, all of that gives them a wider base of experience than the narrow social focus of public school.
That being said, it's pretty easy to make sure your kids get plenty of socializing time with kids close to their ages. Find out what their interests are, and find extra-curriculars that match up. Girl or Boy Scouts, homeschooling co-ops, local sports clubs, activities at the YMCA or the library, local board game groups, and other school-independent activities abound for kids. Some places have special activities just for homeschooled students that might be held during the daytime hours when other kids are in school. In addition, your kids are socialized every time they participate in family activities, and every time you take them out of the house and interact with the community. Public schools do not hold a monopoly on socialization. Far from it.
In the end, you'll be there to facilitate their social opportunities, and this kind of socialization results in a much better result, since you can nip any bad behavior in the bud as you see it, rather than weeks later when a pattern of bad behavior would finally get reported to you by a public school.
Socialization is much more effective for homeschoolers than for public schooled kids, I believe, because kids' families is much more involved in their lives, and you can tailor social and educational opportunities to the kids' interests rather than their age cohort.