how to iterate from list 1 & list 2 values at a time

I am guessing both the list are going to be of same length and if thats the case then you can enumerate on any one the list and use the index function to get the value from second list as well.

a!localVariables(
local!list1: { "user1", "user2", "user3" },
local!list2: { "userA", "userB", "userC" },
a!forEach(
items: local!list1,
expression: a!map(
contentOwner: fv!item,
qcReviewer: index(local!list2, fv!index, null())
)
)
)

Hello [mention:1bf28746db314580b1a6e5d32121e4b3:e9ed411860ed4f2ba0265705b8793d05] 

You do not need to use both the lists to use in the items. You can use the first list to iterate or the 2nd list considering both have the same length of items. 

a!localVariables(
  local!list1: { "user1", "user2", "user3" },
  local!list2: { "userA", "userB", "userC" },
  a!forEach(
    items: local!list1,
    expression: 'type!yourCDT_here'(
      contentOwners:fv!item,
      qcReviewers:index(local!list2,fv!index,null)
    )
  )
)

The merge() function turns multiple lists into tuples picking items from each list at the same index.

a!localVariables(
  local!list1: { "user1", "user2", "user3" },
  local!list2: { "userA", "userB", "userC" },
  a!forEach(
    items: merge(local!list1, local!list2),
    expression: a!map(
      contentOwners: fv!item[1],
      qcReviewers: fv!item[2],
    )
  )
)