Does each cell have one word or more than one? In other words, how
many spaces do you want to insert?

If only one word in a cell, then:

Sub macro1()
Dim rng As Range
Dim c As Range
Set rng = Sheets("Sheet1").Range("A1:A6")
For Each c In rng
c = Left(c, 3) & " " & Right(c, Len(c) - 3)
Next c
End Sub

Hth,
Merjet